sedimentary
Tufa Rock and Tumbled Gemstones
Calcareous Tufa (Calcium Carbonate, CaCO3)
Hardness: 3-4 (Mohs scale), Color: tan to grey, Luster: dull/earthy, Crystal structure: microcrystalline/vuggy, Specific gravity: low due to porosity
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Physical properties
Hardness: 3-4 (Mohs scale), Color: tan to grey, Luster: dull/earthy, Crystal structure: microcrystalline/vuggy, Specific gravity: low due to porosity
Formation & geological history
Formed by the precipitation of carbonate minerals from ambient temperature water bodies such as springs, lakes, and rivers. Often contains imprints of organic material.
Uses & applications
Tufa is used as a decorative landscape garden stone and in aquaculture. The small stones inside include tumbled Lapis Lazuli and Agate, used for jewelry and collections.
Geological facts
Tufa is often confused with travertine, but it is much more porous and less dense. It grows relatively quickly in geological terms around calcium-rich springs.
Field identification & locations
Identified by its extremely lightweight, pitted, and porous 'sponge-like' appearance. Common in limestone regions and thermal spring areas.
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